2,125 research outputs found
Typification of Heliotropium and Tournefortia (Heliotropiaceae) species described by Ruiz and Pavón
Lectotypes are designated here for 14 names proposed by Ruiz and Pavón in
“Flora peruviana, et chilensis” (1799) that were either described or are
currently recognized as members of the genera Heliotropium or Tournefortia
(Heliotropiaceae): Heliotropium corymbosum, H. incanum, H. lanceolatum, H.
microcalyx, H. microstachyum, H. oppositifolium, H. pilosum, H. synzystachyum,
Lithospermum aggregatum, Tournefortia angustiflora, T. longifolia, T.
polystachya, T. undulata, T. virgata. Currently accepted names and comments on
typifications and taxonomic affinities are also provided
The light chain of tetanus toxin inhibits calcium-dependent vasopressin release from permeabilized nerve endings
The effects of tetanus toxin and its light and heavy chain subunits on vasopressin release were investigated in digitonin-permeabilized neurosecretory nerve terminals isolated from the neural lobe of the rat pituitary gland. Exocytosis was induced by challenging the permeabilized nerve endings with micromolar calcium concentrations. Tetanus toxin inhibited vasopressin release only in the presence of the reducing agent dithiothreitol. This effect was irreversible. The purified light chain of tetanus toxin strongly inhibited exocytosis in a dose-dependent manner with half-maximal effect at c. 10 nM. The action of the light chain was observed after only 2.5 min of preincubation. Separated heavy chain subunit had no effect on hormone secretion. Inhibition of vasopressin release could be prevented by preincubating the light chain of tetanus toxin with an immune serum against tetanus toxin.
The data clearly demonstrate that in mammalian neurosecretory nerve endings tetanus toxin acts at a step downstream from the activation by Ca2+ of the exocytotic machinery and that the functional domain of this toxin is confined to its light chain
Phylogenie und Systematik der Gefäßpflanzen
Das Lehr- und Lernposter „Stammbaum der Tracheophyten – Phylogenie und
Systematik der Gefäßpflanzen“ gibt einen Überblick a) über die Phylogenie
(Stammesgeschichte) der „Farnverwandten“ (Lycophyten und Monilophyten, die
„Farne“) bis zu den Familien und b) über die Gymnospermen (Nacktsamer) bis zu
den Gattungen. Innerhalb des Baumes werden die hauptsächlichen ursprünglichen
und abgeleiteten Merkmale (Plesio- und Apomorphien) sowie typische anatomische
und morphologische Merkmale bis zur Stufe der Familien (Gymnospermen) bzw.
Ordnungen (Farnpflanzen) und höherer Gruppen aufgeführt. Die farbliche
Abstimmung der Großgruppen erleichtert das Lehren und Lernen. Das Poster ist
das zweite in einer Reihe, die die Phylogenie der Landpflanzen darstellt.
Poster 1 umfasst die Angiospermen (Blütenpflanzen), Poster 3 die „Moose“
(Leber-, Laub- und Hornmoose). In einer Zusammenarbeit mit international
renommierten Botanikern sind wir bemüht, die Poster in eine Vielzahl anderer
Sprachen übersetzen zu lassen.Stand: Juli 201
Systematics and Chatacteristics
The "Tracheophyte Phylogeny Poster – Vascular Plants - Systematics and
Characteristics" is an educational tool presenting an overview of the
evolutionary relationships among non-flowering vascular plants (lycophytes,
monilophytes, and gymnosperms). The phylogenetic tree depicts the orders and
families (lycophytes and monilophytes) and the genera of gymnosperms, listing
the main apomorphies and plesiomorphies as well as diagnostic and
nondiagnostic anatomical and morphological features within the tree. The
intuitive color-coding facilitates memorization and teaching. Translations of
the poster by internationally renown botanists in various world languages is
in progress. This is one in a series of three educational posters on the
phylogeny of land plants: Poster 1: "Angiosperms", Poster 2: "Tracheophytes:
Lycophytes, Ferns, Gymnosperms", Poster 3: "Bryophytes: Liverworts, Mosses,
Hornworts"
an annotated, synonymic inventory, with links to the protologues and mention of original material
Background An inventory is presented of all names so far validly published in
Cynoglossum sensu lato and its segregate genera: Adelocaryum, Afrotysonia,
Kuschakewiczia, Lindelofia, Mattiastrum, Paracaryum, Rindera, Solenanthus,
Trachelanthus, and their synonyms. Names and designations that were not
validly published in the cited place, and later isonyms, are accounted for
when they have been included in the International Plant Name Index (IPNI).
Problems with IPNI entries, including errors and omissions, are discussed, and
the hope is expressed that the present inventory may be of use for fixing
them. New information The inventory, generated from a list of structured data,
is presented in two Supplements, as a searchable HTML document comprising a
sequence of entries with internal cross-links and links to external sources,
in particular to protologues accessible online or, copyright restrictions
permitting, made available as scanned documents via DOIs, and as machine-
readible file. With minor exceptions, all names have been verified in their
original place of publication, and all were nomenclaturally assessed. Colour
coding is used to distinguish between names (in green) pertaining to
Cynoglossum sensu lato, for which complete synonymies are provided; and names
(in orange) pertaining to other genera but published under Cynoglossum or its
segregates. They are listed together with their basionym and the corresponding
correct name (if it exists), but without complete synonymy. Acceptable,
potentially correct names appear in bold-face type, both under a broadly
defined Cynoglossum (for which purpose validation of 81 new combinations and
the name of 1 new species was necessary) and under one or more of its
segregates. When a name was published for a new taxon, original material is
indicated, usually by direct quotation from the protologue. New type
designations are exceptional (two cases), whereas former type designations are
cited whenever known. Furthermore, types and original specimens, especially
when their digital images are available online, are mentioned with their
locations and accession numbers. Comments are added whenever appropriate,
especially to explain nomenclatural assessments that are not self-evident
Creation of model of the photon beam with a treatment planning system PLUNC for ELEKTA Synergy linear accelerator
In the present study, we performed a comparison and selection of the most appropriate treatment plan with an educational treatment planning system PLUNC which was provide recommended absorbed dose of ionizing radiation in tumor volume, and the minimum value of the dose in organs at risk and normal tissues surrounding the tumor. For this reason, was created model of the photon beam for ELEKTA Synergy Linear Accelerator. The treatment plan was developed for patients with rectal cancer. The simulation was performed on the basis of actual dicom - images of the tumor, which was obtained with modern medical equipment (computed tomography Aquilion Toshiba). For checking of the simulated plan quality, reference dose and dose rate measurements were performed. Present study demonstrates the relationship between the dose distributions and selected treatment plan. As result of research, was conducted comparison and analysis of algorithms for dose calculation in tissueequivalent environment with a treatment planning system PLUNC. Was developed methodological guide for work in the PLUNC software. Thereby, educational treatment planning system PLUNC was put into operation
Synaptobrevin cleavage by the tetanus toxin light chain is linked to the inhibition of exocytosis in chromaffin cells
Exocytosis of secretory granules by adrenal chromaffin cells is blocked by the tetanus toxin light chain in a zinc specific manner. Here we show that cellular synaptobrevin is almost completely degraded by the tetanus toxin light chain within 15 min. We used highly purified adrenal secretory granules to show that synaptobrevin, which can be cleaved by the tetanus toxin light chain, is localized in the vesicular membrane. Proteolysis of synaptobrevin in cells and in secretory granules is reversibly inhibited by the zinc chelating agent dipicolinic acid. Moreover, cleavage of synaptobrevin present in secretory granules by the tetanus toxin light chain is blocked by the zinc peptidase inhibitor captopril and by synaptobrevin derived peptides. Our data indicate that the tetanus toxin light chain acts as a zinc dependent protease that cleaves synaptobrevin of secretory granules, an essential component of the exocytosis machinery in adrenal chromaffin cells
Introduction of Macromolecules into Bovine Adrenal Medullary Chromaffin Cells and Rat Pheochromocytoma Cells (PC12) by Permeabilization with Streptolysin O: Inhibitory Effect of Tetanus Toxin on Catecholamine Secretion
Conditions are described for controlled plasma membrane permeabilization of rat pheochromocytoma cells (PC12) and cultured bovine adrenal chromaffin cells by Streptolysin O (SLO). The transmembrane pores created by SLO invoke rapid efflux of intracellular 86Rb+ and ATP, and also permit passive diffusion of proteins, including immunoglobulins, into the cells. SLO-permeabilized PC12 cells release [3H]dopamine in response to micromolar concentrations of free Ca2+. Permeabilized adrenal chromaffin cells present a similar exocytotic response to Ca2+ in the presence of Mg2+/ ATP. Permeabilized PC12 cells accumulate antibodies against synaptophysin and calmodulin, but neither antibody reduces the Ca2+-dependent secretory response. Reduced tetanus toxin, although ineffective when applied to intact chromaffin cells, inhibits Ca2+-induced exocytosis by both types of permeabilized cells studied. Omission of dithiothreitol, toxin inactivation by boiling, or preincubation with neutralizing antibodies abolishes the inhibitory effect. The data indicate that plasma membrane permeabilization by Streptolysin O is a useful tool to probe and define cellular components that are involved in the final steps of exocytosis
Evidence for nonallopatric speciation among closely related sympatric Heliotropium species in the Atacama Desert
The genetic structure of populations of closely related, sympatric species may
hold the signature of the geographical mode of the speciation process. In
fully allopatric speciation, it is expected that genetic differentiation
between species is homogeneously distributed across the genome. In
nonallopatric speciation, the genomes may remain undifferentiated to a large
extent. In this article, we analyzed the genetic structure of five sympatric
species from the plant genus Heliotropium in the Atacama Desert. We used
amplified fragment length polymorphisms (AFLPs) to characterize the genetic
structure of these species and evaluate their genetic differentiation as well
as the number of loci subject to positive selection using divergence outlier
analysis (DOA). The five species form distinguishable groups in the genetic
space, with zones of overlap, indicating that they are possibly not completely
isolated. Among-species differentiation accounts for 35% of the total genetic
differentiation (FST = 0.35), and FST between species pairs is positively
correlated with phylogenetic distance. DOA suggests that few loci are subject
to positive selection, which is in line with a scenario of nonallopatric
speciation. These results support the idea that sympatric species of
Heliotropium sect. Cochranea are under an ongoing speciation process,
characterized by a fluctuation of population ranges in response to pulses of
arid and humid periods during Quaternary times
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